Organic electroluminescent display device and method of driving the same

Abstract

An organic electroluminescent display device includes a plurality of pixels, each one of the plurality of pixels including: a switching transistor that is connected to a gate line and a data line; a driving transistor, wherein a data voltage of the data line passing through the switching transistor is reflected into a gate of the driving transistor; a sampling transistor that samples a threshold voltage of the driving transistor, wherein a gate of the sampling transistor is connected to a control line, and the sampled threshold voltage is reflected into the gate of the driving transistor; an initializing transistor, wherein a gate of the initializing transistor is connected to a previous or next gate line, and an initialization voltage passing through the initializing transistor is reflected into the gate of the driving transistor; and an organic light emitting diode that is connected to the driving transistor, wherein a driving current of the organic light emitting diode is adjusted according to a voltage of the gate of the driving transistor.

What is claimed is: 
     
       1. An organic electroluminescent display device, comprising:
 a plurality of pixels, each one of the plurality of pixels including:
 a switching transistor connected to a gate line and a data line; 
 a driving transistor, wherein a data voltage of the data line passing through the switching transistor is reflected into a gate of the driving transistor; 
 a sampling transistor that samples a threshold voltage of the driving transistor, wherein a gate of the sampling transistor is connected to a control line, and the sampled threshold voltage is reflected into the gate of the driving transistor; 
 an initializing transistor, wherein a gate of the initializing transistor is connected to a next gate line, and an initialization voltage, which is different from the threshold voltage, passing through the initializing transistor is reflected into the gate of the driving transistor, wherein the voltage at the gate of the driving transistor is equivalent to the initialization voltage when the initializing transistor is turned on, and wherein the initialization voltage applied to the gate of the driving transistor is lower than a second driving voltage; and 
 an organic light emitting diode that is connected to the driving transistor, wherein a driving current of the organic light emitting diode is adjusted according to a voltage of the gate of the driving transistor, 
 
 wherein a first pixel of the plurality of pixels maintains an initialized state and does not emit light during a first frame, and a second pixel of the plurality of pixels maintains an initialized state and does not emit light during a second frame that alternates with the first frame, 
 wherein, during the first frame, a sampling transistor of a third pixel of the plurality of pixels is not enabled when an initializing transistor of the first pixel of the plurality of pixels is enabled, and 
 wherein, during the second frame, a sampling transistor of a fourth pixel of the plurality of pixels is not enabled when an initializing transistor of the second pixel of the plurality of pixel is enabled. 
 
     
     
       2. The device according to  claim 1 , wherein at least one of the switching transistor, the driving transistor, the sampling transistor, and the initializing transistor is a n-type or p-type transistor. 
     
     
       3. The device according to  claim 1 , wherein the initialization voltage has a value such that the organic light emitting diode does not emit light. 
     
     
       4. The device according to  claim 3 , wherein, in the first and the second frames, a control voltage of the control line is transitioned high prior to a gate voltage of the gate line. 
     
     
       5. The device according to  claim 1 , wherein the each one of the plurality of pixels further includes a capacitor connected to the gate and a source of the driving transistor. 
     
     
       6. The device according to  claim 1 , wherein the each one of the plurality of pixels further includes a first capacitor connected to a drain of the switching transistor and a driving voltage source, and a second capacitor connected to the drain of the switching transistor and the gate of the driving transistor. 
     
     
       7. A method of driving an organic electroluminescent display device, comprising:
 initializing a first pixel of a plurality of pixels with an initializing voltage without simultaneously sampling a third threshold voltage of a driving transistor of a third pixel in a first frame; 
 writing a first data voltage into a second pixel of the plurality of pixels in the first frame, whereby the second pixel emits light according to the first data voltage; 
 writing a second data voltage into the first pixel in a second frame, whereby the first pixel emits light according to the second data voltage; and 
 initializing the second pixel with the initializing voltage without simultaneously sampling a fourth threshold voltage of a driving transistor of a fourth pixel in the second frame, 
 wherein the first and the second frames are alternatingly repeated, 
 wherein the first and the second pixels are connected to two consecutive gate lines, respectively, 
 wherein each of the plurality of pixels includes a driving transistor and an organic light emitting diode, 
 wherein the driving transistor adjusts a current applied to the organic light emitting diode according to a voltage of a gate of the driving transistor, 
 wherein the first pixel maintains the initialized state and does not emit light during the first frame, and the second pixel maintains the initialized state and does not emit light during the second frame, and 
 wherein each of the plurality of pixels includes an initializing transistor for initialization thereof with the initializing voltage which is different from a threshold voltage of the driving transistor, 
 wherein a gate of the initializing transistor is connected to a next gate line and the voltage at the gate of the driving transistor is equivalent to the initialization voltage when the initializing transistor is turned on, and 
 wherein the initialization voltage applied to the gate of the driving transistor is lower than a second driving voltage. 
 
     
     
       8. The method according to  claim 7 , further comprising:
 sampling a first threshold voltage of the driving transistor of the first pixel in the second frame before writing the second data voltage into the first pixel, wherein the sampled first threshold voltage is reflected into the gate of the driving transistor of the first pixel; and 
 sampling a second threshold voltage of the driving transistor of the second pixel in the first frame before writing the first data voltage into the second pixel, wherein the sampled second threshold voltage is reflected into the gate of the driving transistor of the second pixel. 
 
     
     
       9. The method according to  claim 7 , wherein initializing the first pixel with the initialization voltage includes turning on an initializing transistor of the first pixel according to an on-level gate voltage of a gate line next to the gate line connected to the first pixel, and
 wherein initializing the second pixel with the initialization voltage includes turning on an initializing transistor of the second pixel according to an on-level gate voltage of a gate line next to the gate line connected to the second pixel. 
 
     
     
       10. The method according to  claim 7 , wherein the driving transistor of each of the first and the second pixels is turned off according to the initialization voltage. 
     
     
       11. The method according to  claim 7 , wherein each of the plurality of pixels further includes a capacitor connected to the gate and a source of the driving transistor. 
     
     
       12. The method according to  claim 7 , wherein each of the plurality of pixels further includes a switching transistor, a first capacitor connected to a drain of the switching transistor and a driving voltage source, and a second capacitor connected to the drain of the switching transistor and the gate of the driving transistor.